Cathode ray tube

Abstract

A cathode ray tube having a fluorescent screen of a copper and aluminum activated zinc sulfide phosphor (ZnS:Cu,Al). The ZnS:Cu,Al phosphor has a Cu activator value ranging from 3x10-4 to 5x10-3 grams per 1 gram of ZnS; an emission color point within a yellowish green region in the color coordinates of CIE color system represented by values x and y ranging from 0.295 to 0.370 and 0.570 to 0.630, respectively; a color point of body color within a yellow region in the color coordinates of CIE color system represented by values x and y ranging from 0.380 to 0.400 and 0.390 to 0.440, respectively; and a mean reflectance in the visible spectrum region of not less than 75% when the mean reflectance of a magnesium oxide diffusion plate is defined to be 100%.

We claim: 
     
       1. A cathode ray tube having a fluorescent screen including, as a green light emission component, a phosphor consisting essentially of a copper and aluminium activated zinc sulfide phosphor, the amount of said copper being within the range of 4×10 -4  to 3×10 -3  grams per 1 gram of said zinc sulfide, the emission color point of said phosphor lying within a yellowish green region in the color coordinates of CIE color system represented by values x and y ranging from 0.300 to 0.370 and 0.570 to 0.630, respectively, the color point of the body color of said phosphor lying within a yellow region in the color coordinates of CIE color system represented by values x and y ranging from 0.380 to 0.400 and 0.390 to 0.440, respectively, and the mean reflectance in the visible spectrum region of said phosphor being not less than 75% when the mean reflectance of a magnesium oxide diffusion plate is defined to be 100%.